Surface Condition Monitoring Of Railway Tracks

ABSTRACT

A network of monitoring devices for monitoring the condition of the surface of railway track rails is described. A monitoring device includes a spectrometer configured to monitor at least one frequency that indicates the presence of a contaminant on a railway track rail and to provide an output indicative of the presence or absence of the contaminant on a railway track rail. The monitoring device also includes a transmitter arranged to transmit its output to a central database. The central database is configured to store data from the monitoring devices in the network over time, establishing historical data of track conditions as monitored by the monitoring devices. A comparator is configured to compare current track conditions over the network with historical track conditions over the network, providing an indication of likely developments of track conditions.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is the U.S. National Stage application of International ApplicationNo. PCT/ GB2021/050850, filed Apr. 6, 2021, which claims the benefit ofpriority from GB Application No. 2004903.7, filed Apr. 2, 2020. Theentire contents of these prior applications are incorporated byreference herein.

FIELD

This invention pertains generally to the field of surface monitoring,and in particular surface condition monitoring devices for use onrailway track rails to help monitor and maintain the optimum conditionof rail to wheel interface.

BACKGROUND

The surface condition of railway tracks presents a real challenge torail network operators who must ensure that they are well maintained andkept in optimum condition for the passage of rail vehicles. The railwaytrack rails, typically made from steel, are subjected to considerableforces from passing vehicles that can cause surface and structural wear,whilst also being exposed to adverse and frequently changeable weatherconditions, along with other environmental hazards throughout the year.The rail to wheel interface, typically steel against steel, provides anenergy efficient combination, yet this interface can prove to be highlysensitive to contamination. Precipitation, dew, leaf fall, localisedtemperature changes, extreme weather conditions, vegetation and otherdetritus, are just some of the events that can affect the surfacecondition of the rail track, and therefore the passage of the railvehicle passing thereon. The majority of these contaminants havesignificant water content, which affects adhesion of the wheel on therail surface.

Contaminants can be referred to as a ‘third layer’ between first andsecond layers which are respectively the railway track rail and therailway vehicle wheel, or vice versa.

The smooth, safe and efficient running of a rail vehicle relies upon thefriction between the steel rails and the steel wheels. Fundamental topredictable and optimised braking of a rail vehicle using conventionalbrakes, is creating a reliable rail to wheel interface that hassufficient friction for the desired rate of deceleration. Friction canbe reduced when the rails become slippery or greasy, often because ofrain, dew, fluids such as oil or even decomposing leaves that fall ontothe line and can become compacted. This can result in a chemicalreaction occurring between the water soluble leaf component and steelrail coating. This coating is semi-permanent and therefore it may taketime to be sufficiently worn away by the passage of trains. Suchvariance and unpredictability to surface conditions of the rail tracksin terms of moisture and detritus can present a real challenge tonetwork operators. They must predict the likelihood of low frictionconditions being experienced by a passing vehicle, causing the vehicleto slip, before this happens, and take steps to minimise the impact.They must carry out ongoing monitoring of track conditions to flag upareas of concern and again take steps to rectify these. They must ensurethat trains are adequately spaced along the line to ensure that requiredstopping distances are taken into account in light of changeable surfaceconditions. With such conditions subject to change at any moment,particularly environmental conditions due to changeable weather, it isvery common for issues to occur. Rail network operators are quick todelay or cancel trains, rather than risk passenger safety. Timetablesare often altered for different seasons, such as in the UK, regularAutumnal timetabling takes steps to anticipate these delays during theleaf fall season. This comes at considerable cost to the rail industry.It was estimated that leaves on the line cost around £60million indirect costs each year in the UK alone, which is estimated to amount toaround £350million societal costs.

A loss of friction at the rail to wheel interface effects traction whenthe train first sets off and starts moving, which in the case of freighttrains, affects hauling capability. The wheels can be caused to spin,and in some instances the train is unable to move. These low frictionconditions result in poor adhesion between the wheel to rail interface,also causing issues when braking and coming to a stop. Substantial lossof friction results in reduced braking forces, meaning that stoppingdistances are considerably longer and this must be accounted for whendispatching trains within the rail network. In extreme cases the wheelsmay even lock, causing the train to go into a slide. This can causeconsiderable damage to the wheel and rail track. Station platforms mayalso be overshot where a driver has not allowed a sufficient distance tobring the train to a standstill.

Snow and ice, when deposited on rail tracks, can cause such low adhesionconditions to occur, making rail vehicles prone to slide or slip duringbraking, whilst also causing the train to encounter difficulties pullingaway. But less obvious conditions such as light rain following a spellof dry weather, or morning dew on the rails, can also cause challengingrail conditions for the rail networks to account for. The effect on thesurface condition of the rail tracks may only be short term, but theunpredictable nature of such effects may be sufficient for a significantincident to occur to a passing rail vehicle. Tests have shown that thereis a strong correlation between low adhesion incidents and theoccurrence of the dew point, where water vapour from the air condensesonto the railhead forming a fluid film. This fluid film leads to a lossof traction at the wheel to rail interface.

Other contributing factors are thought to include the move from brakeshoes to disc brakes, which means that some surface cleaning andconditioning of the rails no longer occurs by abrasion. It is alsothought that rail network operators no longer have to carry outsufficient lineside maintenance that would have been essential duringthe steam locomotive era, to prevent vegetation from catching fire. Theextra growth from vegetation increases the supply of leaves and theincrease of leaf fall onto the line, thereby exacerbating the problem.It may also affect the dew point and localised climate in some areas. Inextreme cases, the build-up of leaf matter can electrically insulate thewheels from the rails, resulting in signal failure. This can cause anevent such as Wrong Side Track Circuit Failure, or WSTCF, when leafmatter electrically insulates the wheels from the rails resulting insignal failure. Other events such as Signal Passed at Danger, or SPAD,can also occur when a train slides past a signal because it could notstop.

Rail vehicles are typically fitted with wheel slide protection, in anattempt to counter slippery rail conditions. When wheels become locked,flat spots can be ground into the steel rims, especially if the wheel isstill sliding when entering a non-slippery portion of rail track. Thiscan cause wheel flats, where the wheel shape has been altered from itsoriginal profile, leading to severe vibrations and the need forreprofiling of the wheels, or even wheel replacement, at considerableexpense.

Numerous different ways of surface conditioning the rail tracks to dealwith such changeable circumstances have been tried, and many are inoperation. These range from applying a jet to blast away any deposits ordetritus, such as with water jets alongside a mechanical scrubbingapparatus of some form. Laser blasting the rails has also been tried andtested. Or coating the rail tracks and/or wheels with a high frictionmaterial, such as by depositing sand as a paste or otherwise, or theapplication of adhesion modifying chemicals, onto the rail. The sandassists adhesion during braking and acceleration. However, using sandmay increase the risk of unwanted insulation, and therefore may alsocontain metal particles. For an example, an adhesion modifier such asSandite™, a combination of sand, aluminium particles and adhesive.Blasting or coating the rails with sand and substances such as Sandite™is not thought to offer an economically sound solution, nor is itthought to be environmentally friendly to release these substances intothe environment. Alternative coatings currently in use include TrackGrip 60™ (TG60™) an adhesion enhancer for rails, or Electragel, whichconsists of steel particles and sand, suspended in a gel. To attempt tocombat the issues experienced by moisture and the formation of dew onthe rail tracks, and thereby improve both traction and impedanceproperties, the rails have typically been treated with hydrophobicproducts. To apply these coating or treatments to the rail trackstypically requires special trains or rail vehicles, and may also involvemanual or application by hand. In the UK these vehicles typicallyinclude Rail Head Treatment Trains or RHTTs, or Multi-Purpose Vehiclesor MPVs. Again, a challenge for the rail network operators to factorinto the overall operation of the network, ensuring the passage of suchrail vehicles, or the application of such coating and substances attimes when the track is not in use.

At specific sites, or portion of rail track, where significant lowadhesion regularly occurs, such as on the approach to a station,traction gel applicators may have been installed. These apply liquid tothe railhead as a rail vehicle passes therethrough.

These processes are only effective for a short period of time. Jetblasting the rail track is ineffective as soon as the next leaf falls,or is deposited onto the rails due to the aerodynamic turbulence of apassing train, or other detritus lands along the line. Sand and othertreatment products deposited directly onto the rail track or railheadmay prove more durable, but these substances can be easily washed awayby rainfall.

For the majority of these surface conditioning processes, the initialdecision to condition the surface is made speculatively, and largelybased on sight. An operator takes a look at a stretch of track, or makesa decision based on recent or imminent environmental conditions.Alternatively, a track is conditioned at predetermined intervalsregardless of any specific indicator that a portion of track has reacheda poor level.

The prior art shows a number of devices which attempt to address theseneeds in various ways.

GB 2 355 702 (LaserThor Ltd) discloses a method of cleaning a rail byremoving contaminants from the surface of the rail. The method comprisesthe steps of generating a high intensity pulsed laser beam and directingthe laser beam onto the surface of the rail so as to destroy at leastpart of the contaminants. The laser beam may be operated in response todetection of the contaminants. This control system comprises a lightsource and a tube which directs a light beam from the source to thesurface of the rail, where the beam is reflected. A further tubecollects the reflected beam and passes it to a prism which forms part ofa spectrometer. The identity of many substances, such as leaves or othercontaminants, can be determined by the analysis of the wavelengths ofthe light in a composite beam reflected off the surface of an objectmade from the substance by using a spectrometer. The control unitdetermines the nature of the substance from which the light beam hasbeen reflected. Whilst providing a means of determining a type ofcontamination on a rail surface, this arrangement presents accuracyissues and a considerable amount of sensing noise that leads to unclearresults. It is also somewhat limited to the range of contaminants ormaterials that it is able to detect.

BRIEF SUMMARY

Whilst the prior art attempts to address the issue of detecting thepresence of various contaminants on a rail track, it provides no way ofevaluating current conditions and predicting future conditions over arail network.

Preferred embodiments of the present invention aim to provide a networkof surface monitoring devices that may be improved in this respect.

According to one aspect of the present invention, there is provided anetwork of monitoring devices for monitoring the condition of thesurface of railway track rails, each of the monitoring devicescomprising a spectrometer configured to monitor at least one frequencythat indicates the presence of a contaminant on a railway track rail andto provide an output indicative of the presence or absence of thecontaminant on a railway track rail, and each of the monitoring devicescomprising a transmitter arranged to transmit its output to a centraldatabase.

Preferably, each spectrometer is configured to monitor a plurality offrequencies that indicate the presence of contaminants on a railwaytrack rail.

Preferably, each spectrometer is a Raman spectrometer.

Preferably, the monitoring devices comprise one or more of thefollowing: handheld device, railway vehicle borne device, track sidedevice, drone mounted device, UAV mounted device, satellite mounteddevice.

Preferably, said contaminants to be monitored comprise at least one fromthe group consisting of Cellulose, Cellulose Acetate and Tyrosine.

Each monitoring device may be configured to compare a monitored valuewith one or more predetermined value and to provide a correspondingdevice output that indicates whether the condition of a monitoredrailway track rail is above or below a predetermined acceptable level.

Preferably, each spectrometer output is indicative of both type andamount of contaminant.

Preferably, each monitoring device includes an operating interfacewhereby a user can control operation of the monitoring device.

A network according to any of the preceding aspects of the invention mayfurther comprise at least one surface conditioning device that isoperative to condition the surface of one or more railway track rail inresponse to data received.

Said surface conditioning device may be operative to condition a railwaytrack rail by means of plasma delivered to the rail.

Preferably, at least some of said transmitters are wirelesstransmitters.

Preferably, the central database is configured to store data from themonitoring devices over time, thereby to establish historical data oftrack conditions as monitored by the monitoring devices.

Preferably, a network according to any of the preceding aspects of theinvention further comprises a comparator that is configured to comparecurrent track conditions over the network with historical trackconditions over the network, thereby to provide an indication of likelydevelopments of track conditions.

The method extends to a method of monitoring the condition of thesurface of railway track rails of a rail network, the method comprisingoperating monitoring devices of a network according to any of thepreceding aspects of the invention to indicate the presence or absenceof contaminants on the rails at various locations throughout thenetwork.

Such a method may comprise the further step of operating at least onesurface conditioning device to condition the surface of a rail inresponse to data received from the monitoring devices.

The surface conditioning may be carried out on a railway vehicle as ittravels along the railway track rail. The method may be carried out asthe railway vehicle makes multiple passes along the railway track rail.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention, and to show how embodimentsof the same may be carried into effect, reference will now be made, byway of example, to the accompanying diagrammatic drawings, in which:

FIG. 1 shows one embodiment of surface monitoring device as a handhelddevice, in use, monitoring the surface condition of a rail, withenlarged view of the handheld device;

FIG. 2 shows a further embodiment of surface monitoring device mountedtrack side, showing a pair of devices, in use, monitoring the conditionof a rail, with enlarged side view of one of the track side devices;

FIG. 3 shows one embodiment of surface monitoring device when mounted toa railway vehicle, showing a surface monitoring device mounted at thefront of the vehicle, and a further surface monitoring device mounted atthe rear of the railway vehicle, with surface conditioning devicebetween;

FIG. 4 shows a further embodiment of surface monitoring device whenmounted to a locomotive, with enlarged view of the undercarriage of thelocomotive;

FIG. 5 shows one embodiment of surface monitoring device as a schematicdiagram, showing the component parts that allow the surface monitoringdevice to detect the presence of a material on a surface, and analysethe composition of the material on that surface;

FIG. 6 shows one embodiment of a network of surface monitoring devicesalong a single track, mounted on railway vehicles, track side and as ahandheld device, relaying surface condition data to a central databasefor evaluation; and

FIG. 7 shows one embodiment of a central database obtaining surfacecondition data from a wider rail network.

In the figures, like references denote like or corresponding parts.

DETAILED DESCRIPTION

It is to be understood that the various features that are described inthe following and/or illustrated in the drawings are preferred but notessential. Combinations of features described and/or illustrated are notconsidered to be the only possible combinations. Unless stated to thecontrary, individual features may be omitted, varied or combined indifferent combinations, where practical.

FIG. 1 shows one embodiment of surface monitoring device 1, in use by anoperator, typically a Mobile Operations Manager (MOM), to monitor thesurface condition of an area of rail 2. A Mobile Operations Manager isthe person responsible for checking rail track condition. They decidewhen to clean the rail track and confirm that the track is at a suitablelevel for normal operation.

The surface monitoring device 1 is a handheld device 6, and is portable,and easy to for the operator to carry about for measuring differentsurfaces. FIG. 1 shows the handheld device 6 being held against or closeto the surface of the rail 2, and also shows an enlarged view or closeup of the handheld device 6. This shows one possible configuration ofoperating interface 4, that controls spectrometer 3, to take a readingof the rail 2. The handheld device 6 may be configured to detect andanalyse a specific combination of contaminants on the surface, or it maystore this data for later download and analysis. Alternatively, thehandheld device 6 may wirelessly transmit this data to a base station,not shown, to allow a central resource to analyse rail conditionsthroughout a network, and send out various surface cleaning andconditioning devices in response to this data.

FIG. 2 shows another embodiment of surface monitoring device 1, wherethe device is incorporated into a pillar, mounted by the side of arailway track, for monitoring a portion of rail 2. A spectrometer 3shown in such an arrangement is transmitting recorded data back to acentral resource through a transmitter 19. The enlarged view of one ofthese surface monitoring devices 1 shows that one device can be arrangedto monitor the condition of two rails 2 at the same time, or as and whenrequired. A monochromatic light source 8, such as a laser, transmits alaser beam in the direction of the rail 2 on one side of the track, anda further monochromatic light source 8, transmits a laser beam to bounceoff the rail 2 on the other side of the track, thus monitoring bothrails 2 at the same time. These surface monitoring devices 1 may bepositioned at predetermined intervals along a railway line, sufficientto cover the majority of rails 2 within a network, or may be installedin areas where surface condition of the rails 2 is of a particularconcern.

FIG. 3 shows yet a further embodiment of surface monitoring device 1when mounted to the undercarriage of a railway vehicle 17. In thisparticular railway vehicle 17, there is a surface monitoring device 1 atthe front end of the railway vehicle 17, and a further surfacemonitoring device 1 towards the rear of the railway vehicle 17. Mountedsomewhere between these surface monitoring devices 1 is a surfaceconditioning device 5. The arrangement of both front and rear surfacemonitoring devices 1 allows an operator to determine the effectivenessof the surface conditioning device 5. There may be any number of surfacemonitoring devices 1 mounted along a railway vehicle 17, and configuredto act upon the rails 2 along which the railway vehicle 17 is passing.There may also be any number of surface conditioning devices 5, tosurface condition a section of rail 2 as many times as is required toachieve a suitable reading of surface condition by the last surfacemonitoring device 1.

The surface conditioning device 5 in such an arrangement may compriseany number of different ways of conditioning the surface, such as jetblasting with water alongside mechanical scrubbing apparatus, laserblasting, applying a coating of high friction material, depositing sandor applying surface modifying chemicals. The arrangement of surfacemonitoring devices 1 being before and after the surface conditioningdevice 5 allows an operator to monitor performance of the surfaceconditioning device 5, and make any required changes to this surfaceconditioning device 5 to ensure that the condition of the rail 2 isoptimised.

This railway vehicle 17 may incorporate the operating interface 4 withinthe driver’s cabin. A driver may be presented with the results of thesurface monitoring device 1 on a driver display 18. This is to allow thedriver to alter how they drive the railway vehicle 17 in response to theresults of condition of the rails 2. For an example, the driver may needto increase stopping distances, should the reading from the surfacemonitoring device 1 suggest the presence of contaminants, or anincreased risk of slip. Likewise, the results may allow an increase inspeed, safe in the knowledge that the condition of the rails 2 has beenoptimised. The driver may also be provided with information on thedriver display 18 that directs them to switch on any onboard surfaceconditioning devices 5, having identified a poor condition of rail 2along which the railway vehicle 17 is passing. The railway vehicle 17 inFIG. 3 is specifically for cleaning and conditioning railway track rails2. The surface monitoring devices 1 allow such a railway vehicle 17 todirectly respond to a change in surface condition, whilst also providingthe operator with real-time feedback as to the cleaning performance oftheir railway vehicle 17. The operator is then able to adjust theirlevel of cleaning and conditioning of a section of rail 2 accordingly,rather than simply cleaning all rails 2 by the same amount, or by makinga decision of cleaning level by sight alone.

FIG. 4 shows a further arrangement of surface monitoring device 1 whenmounted to the undercarriage of a passenger carrying railway vehicle 17.The close-up shown shows the surface monitoring device mounted to theundercarriage, and configured such that the monochromatic light source 8of the spectrometer 3 acts directly upon the rail 2. The driver’s cabmay again be provided with the operating interface 4 to control theoperation of the surface monitoring device 1, and may also comprise adriver display 18. This driver display 18 may relay the data recorded bythe surface monitoring device 1 directly to the driver, or it mayprocess this data to provide top-level information to the driver, toallow them to instantaneously alter their driving according to real-timerail conditions. For an example, the surface monitoring device 1 mayfeed through rail condition data that falls outside of predeterminedparameters, indicating that a particular section of rail 2 is not in anoptimum condition. This may simply be shown to a driver as a red flag,that enables them to make an instant decision to allow more time todecelerate, allowing for greater stopping distances, and to reduce theirspeed until the data recorded falls back within an optimal range.

In all embodiments, display 4 may indicated detailed data representingthe condition of monitored rails 2. Additionally or alternatively, itmay simply indicate if the condition of a monitored rail is either GOODor BAD - indicated in FIG. 1 by a tick or a cross. This enables a driveror MOM to respond quickly to either change speed or request trackconditioning, without having to spend time analysing more detailed data.

By mounting surface monitoring devices 1 to a considerable number ofrailway vehicles 17 running within a rail network, a rail operator canbuild up a much bigger picture of rail condition throughout the entirenetwork, on an instantaneous basis, and be better prepared to react toany sudden changes to environmental conditions, that lead to poor railconditions. This vastly improves the safety of the rail network,allowing for surface conditioning to be directed towards specific areasof concern.

FIG. 5 shows a schematic diagram of one possible arrangement of surfacemonitoring device 1, comprising a probe 9 for directing light frommonochromatic light source 8 onto a surface. The monochromatic lightsource 8 is likely to be a laser, and therefore this laser is configuredto transmit laser beams 14 onto a surface through the probe 9.Electromagnetic radiation from the surface, in the form of scatteredphotons 15, is collected by a lens within spectrometer 3, and sentthrough a grating 11. The grating 11 filters out any noise, orinterference within the light of a wavelength that corresponds with thatof the original laser beam 14, whilst allowing the remaining collectedlight to be dispersed into a detector 12. These components may becontained within a housing, such as the handheld device 6 of FIG. 1 , orit may be contained within a housing that is suitable for mounting ontothe undercarriage of a railway vehicle 17.

The surface monitoring device 1 is provided with a power supply 16 thatmay be a battery, or may use regenerative power, and that provides asource of power to all of the components that make up the surfacemonitoring device 1.

One type of spectrometer 3 that may be used is a RAMAN spectrometer,which is a form of vibrational spectroscopy. The laser beam 14 is beamedonto the surface of the rail 2, which leads to absorption and scatteringof photons. Most of these scattered photons 15 have identicalwavelengths as the original photons and are therefore termed ‘Rayleighscatter’. However, a very small amount of the scattered photons 15 aremoved to an alternate wavelength, termed ‘RAMAN scatter’. The majorityof these RAMAN scattered photons 15 are moved to greater wavelengths.The original photon leads to excitation of electrons, which move intogreater energy positions, before they fall back to a lower level andradiate a dispersed photon. If the electron falls back to its originallevel, it leads to Rayleigh scattering. However, if the electron fallsback to a different level, then Raman scattering occurs.

The advantages of RAMAN spectroscopy are that it is very effective forchemical examination of a surface due to its high specificity, aqueoussystem compatibility, lack of particular sample preparation, and shorttimescale. Raman bands have an exceptional signal-to-noise ratio and donot overlap. Raman bands are unaffected by water, and therefore goodspectra can be collected from a surface containing considerable watermolecules. The probe 9 with a Raman spectrometer 3 does not have tocontact the rail 2, but the laser beam 14 lights up the rail 2, andmeasures the scattered photons 15. A Raman spectrum can also be amassedin a few seconds, allowing for real-time surface conditions to bemonitored.

By limiting the Raman spectroscopic analysis to frequencies ofparticular interest, corresponding to anticipated contaminants ofinterest, scanning can be carried out much more quickly than ifbroadband frequencies are scanned. This leads to critical data beingavailable to a driver or other operative much more quickly, therebyimproving safety on the railway network.

A laser creating the laser beam performs well as the monochromatic lightsource 8 as it provides a sufficient intensity to generate an effectiveconcentration of Raman scatter therefore permitting a clean spectrum,with little to no extraneous bands. The laser displays excellentwavelength stability and minimal background emission.

The probe 9 collects the scattered photons 15, whilst filtering out theRayleigh scatter and additional background signals from any fibre opticcables. It then transmits this information to the detector 12 via thespectrometer 3 for analysis. The scattered photons initially enter thespectrometer 3 and are transmitted through the grating 11, which acts toseparate them by wavelength, before they are carried to the detector 12.This measures the intensity of the Raman signal at each wavelength,which is then plotted as the Raman spectrum. These frequenciescorrespond to biochemical compounds relevant to leaf materials andtherefore of particular interest to drivers or other operatives.

The surface monitoring device 1 is configured to compare a monitoredvalue with one or more predetermined values and to provide acorresponding device output that indicates whether the condition of therail 2 is above or below a predetermined acceptable level. The Ramanspectrometer output is indicative of both type and amount ofcontaminant.

FIG. 6 shows one example of a plurality of different surface monitoringdevices 1 being used throughout a rail network. These surface monitoringdevices 1 may obtain data from the rails 2 of a single track, or theymay obtain data from rails 2 that make up a much larger network oftracks within a region or country. The surface monitoring devices 1 maybe mounted to various rail vehicles that pass along the tracks, they maycomprise handheld devices 6 for use by an operative, or they may bemounted track side within a pillar or similar, or any combination ofthese that suit a particular run of rails 2. Each of these surfacemonitoring devices 1 is configured to obtain surface condition data,real-time or as and when required, along a length of track within anetwork, and to wirelessly transmit this data to a wireless receiver 21of a central database 20.

A network of surface monitoring devices 1 may form an IoT (Internet ofThings) enabled network of sensors, software and other technologies forconnecting and exchanging data with other devices and/or systems withinthe network over the Internet. The uploading of data from these varioussources of rail condition can be achieved. Each of these data sources ofsurface condition is evaluated against a central database for the fullnetwork. The data is used to predict current conditions elsewhere in thenetwork and also forecasts conditions for the future. With multiplesources running over the same line a real-time development of theadhesion conditions is also possible, not just a snap shot in time. Aspectrometer 3 shown in such an arrangement is transmitting recordeddata back to a central resource through a transmitter 19.

The surface monitoring devices 1 may be positioned at predeterminedintervals along a railway line, sufficient to cover the majority ofrails 2 within a network, or may be installed in areas where surfacecondition of the rails 2 is of a particular concern. Rail networkoperatives may be provided with handheld devices 6 for surfacemonitoring. They may spot a region rail 2 that is of particular concern,or may wish to perform spot checks to monitor a particular tracksection. They may undertake cleaning or maintenance of a section of rail2 and wish to take readings before, during or after this process. Thehandheld devices 6 may wirelessly transmit this data through atransmitter 19 to a central database 20 for analysis. Various surfacecleaning and conditioning devices may be sent out in response to thisdata to condition the section of rail 2 where the reading was taken.

The central database 20 may therefore receive data, real-time or throughdownload, from multiple sources covering a network. These sourcesinclude handheld devices 6 used by track engineering MOMs (MobileOperations Managers) for instantaneous track evaluation; cleaningvehicle mounted for measuring before and after cleaning; passenger orfreight vehicle mounted; track side mounted, positioned near hotspots toaid in prediction of conditions; drone, Unmanned Aerial Vehicle UAV orsatellite mounted. This allows the central database 20 to build up thefull picture of surface condition of rails that make up a rail network.

One example of central database 20, as shown in FIG. 6 , is obtainingsurface condition data along a single rail line. In this example railoperatives MOMs may go out and measure good rail conditions in themorning, using a handheld device 6. However as the rail trafficcontinues to pick up and deposit leaf material, the rail conditions willlikely deteriorate. Vehicle mounted surface conditioning devices thatpass along the rails 2 can read the surface condition and feedback anyincrease in leaf matter, and track side surface monitors can measurematerial being added and removed by passing trains. In this case thetrains may be redepositing material away from the original site. Thenetwork of surface monitoring devices relay all readings to the centraldatabase 20, wirelessly. A comparator 22 associated with the centraldatabase 20 makes use of historical data and other known data on trackconditions, to enable a decision on overall surface condition. If anintervention is needed, a Railhead Treatment Train can be deployed inbetween scheduled trains. Surface condition readings can be taken beforeand after cleaning in a preventative maintenance action at a higherspeed. This causes minimal interruption to the schedule of passingfreight and passenger trains when compared to reactive cleaning of verypoor conditions if further deterioration is allowed. This system willimprove the operational performance of the line in question.

FIG. 7 shows the central database 20 with comparator 22, receiving datathrough a receiver 21 across an entire rail network. The data gatheredover the year, for an example, can be referenced back to a model forgood, transitional and poor conditions. By using the surface monitoringdevices 1 distributed over the network a picture of the currentconditions can be predicted throughout the whole network. Anunderstanding of the changing conditions throughout the network can bemodelled and developed. This can therefore enable interventions forcleaning to be forecast more accurately and scheduled with minimumdisruption to the whole network.

In this specification, the verb “comprise” has its normal dictionarymeaning, to denote non-exclusive inclusion. That is, use of the word“comprise” (or any of its derivatives) to include one feature or more,does not exclude the possibility of also including further features. Theword “preferable” (or any of its derivatives) indicates one feature ormore that is preferred but not essential.

All or any of the features disclosed in this specification (includingany accompanying claims, abstract and drawings), and/or all or any ofthe steps of any method or process so disclosed, may be combined in anycombination, except combinations where at least some of such featuresand/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanyingclaims, abstract and drawings), may be replaced by alternative featuresserving the same, equivalent or similar purpose, unless expressly statedotherwise. Thus, unless expressly stated otherwise, each featuredisclosed is one example only of a generic series of equivalent orsimilar features.

The invention is not restricted to the details of the foregoingembodiment(s). The invention extends to any novel one, or any novelcombination, of the features disclosed in this specification (includingany accompanying claims, abstract and drawings), or to any novel one, orany novel combination, of the steps of any method or process sodisclosed.

1-19. (canceled)
 20. A network of monitoring devices for monitoring acondition of a surface of railway track rails, each of the monitoringdevices comprising a spectrometer configured to monitor at least onefrequency that indicates the presence of a contaminant on a railwaytrack rail and to provide an output indicative of the presence orabsence of the contaminant on a railway track rail, and each of themonitoring devices comprising a transmitter arranged to transmit itsoutput to a central database.
 21. The network of claim 20, wherein eachspectrometer is configured to monitor a plurality of frequencies thatindicate the presence of contaminants on a railway track rail.
 22. Thenetwork of claim 20, wherein each spectrometer is a Raman spectrometer.23. The network of claim 20, wherein the monitoring devices are selectedfrom at least one of a handheld device, railway vehicle borne device,track side device, drone mounted device, UAV mounted device, andsatellite mounted device.
 24. The network of claim 20, wherein saidcontaminants to be monitored comprise at least one member of the groupconsisting of Cellulose, Cellulose Acetate, and Tyrosine.
 25. Thenetwork of claim 20, wherein each monitoring device is configured tocompare a monitored value with one or more predetermined value and toprovide a corresponding device output that indicates whether thecondition of a monitored railway track rail is above or below apredetermined acceptable level.
 26. The network of claim 20, whereineach spectrometer output is indicative of both type and amount ofcontaminant.
 27. The network of claim 20, wherein each monitoring deviceincludes an operating interface whereby a user can control operation ofthe monitoring device.
 28. The network of claim 20, further comprisingat least one surface conditioning device that is operative to conditionthe surface of one or more railway track rail in response to datareceived.
 29. The network of claim 20, wherein said surface conditioningdevice is operative to condition a railway track rail by means of plasmadelivered to the rail.
 30. The network of claim 20, wherein at leastsome of said transmitters are wireless transmitters.
 31. The network ofclaim 20, wherein the central database is configured to store data fromthe monitoring devices over time, thereby to establish historical dataof track conditions as monitored by the monitoring devices.
 32. Thenetwork of claim 20, further comprising a comparator that is configuredto compare current track conditions over the network with historicaltrack conditions over the network, thereby to provide an indication oflikely developments of track conditions.
 33. A method of monitoring acondition of a surface of railway track rails of a rail network, themethod comprising operating monitoring devices of the network of claim 1to indicate the presence or absence of contaminants on the rails atvarious locations throughout the network.
 34. The method of claim 33,comprising the further step of operating at least one surfaceconditioning device to condition the surface of a rail in response todata received from the monitoring devices.
 35. The method of claim 34,wherein the surface conditioning is carried out on a railway vehicle asit travels along the rail.
 36. The method of claim 35, carried out asthe railway vehicle makes multiple passes along the rail.